Spin-Hall effect and circular birefringence of a uniaxial crystal plate

The linear birefringence of uniaxial crystal plates is known since the 17th century, and it is widely used in numerous optical setups and devices. Here we demonstrate, both theoretically and experimentally, a fine lateral circular birefringence of such crystal plates. This effect is a novel example of the spin-Hall effect of light, i.e., a transverse spin-dependent shift of the paraxial light beam transmitted through the plate. The well-known linear birefringence and the new circular birefringence form an interesting analogy with the Goos-H\"anchen and Imbert-Fedorov beam shifts that appear in the light reflection at a dielectric interface. We report the experimental observation of the effect in a remarkably simple system of a tilted half-wave plate and polarizers using polarimetric and quantum-weak-measurement techniques for the beam-shift measurements. In view of great recent interest in spin-orbit interaction phenomena, our results could find applications in modern polarization optics and nano-photonics.Comment: 16 pages, 8 figures, to appear in Optic

Scheduling of Dependent Tasks Application using Random Search Technique

Since beginning of Grid computing, scheduling of dependent tasks application has attracted attention of researchers due to NP-Complete nature of the problem. In Grid environment, scheduling is deciding about assignment of tasks to available resources. Scheduling in Grid is challenging when the tasks have dependencies and resources are heterogeneous. The main objective in scheduling of dependent tasks is minimizing make-span. Due to NP-complete nature of scheduling problem, exact solutions cannot generate schedule efficiently. Therefore, researchers apply heuristic or random search techniques to get optimal or near to optimal solution of such problems. In this paper, we show how Genetic Algorithm can be used to solve dependent task scheduling problem. We describe how initial population can be generated using random assignment and height based approaches. We also present design of crossover and mutation operators to enable scheduling of dependent tasks application without violating dependency constraints. For implementation of GA based scheduling, we explore and analyze SimGrid and GridSim simulation toolkits. From results, we found that SimGrid is suitable, as it has support of SimDag API for DAG applications. We found that GA based approach can generate schedule for dependent tasks application in reasonable time while trying to minimize make-span

A socio-demographic profile, growth, nutritional and hygiene status of children of primary and secondary boarding schools of Gandhinagar district: a cross sectional study

Background: A school is a key location for educating children about health, hygiene and nutrition, and for putting in place interventions to promote the health of children. Objectives: of current study were 1) To study the socio demographic profile of children of boarding schools. 2) To study the growth, nutritional and hygiene status of children of boarding schools.Methods: The study was a cross sectional study. After taking the permission of principal of resident schools and consent of the parents of children, 867 children from 8 boarding schools were interviewed during February-March 2011. A self-administered questionnaire was used for data collection.Results: Age of the study children (total 867) ranged from 5-19 years. (Mean age = 13.80 ± 1.96 years). Out of 867, 434 (49.9%) were boys and 433 (50.1%) were girls. 32.6% belonged to socio economic class IV. There were only 122 (14.1%) children who had been in boarding school since 4 and more than 4 years. Good personal hygiene was observed in only 75 (8.7%) children followed by fair personal hygiene in 292 (33.7%) children and poor personal hygiene in 500 (57.7%) children. 220 (50.8%) female children had fair personal hygiene and 343 (79.0%) male children had poor personal hygiene and this difference was statistically significant. Prevalence of malnutrition in this study was 7.2% (Females = 4.2%; Males = 10.1%; P <0.001).The bulk of the malnutrition cases were constituted by the grade-I P.E.M. cases (66.1%) followed by grade-II P.E.M. cases (25.8%) and there were 5 (8.1%) cases of grade-III malnutrition only in female children. Conclusion:Poor personal hygiene, poor nutritional status among these children needs great attention and health education.

Modeling fracture cementation processes in calcite limestone: a phase-field study

The present work investigates the influence of crack opening rates on the development of four important calcite vein morphologies, namely fibrous, elongate-blocky, partially open, and euhedral, as a result of bitaxial growth in syntaxial veins using a multiphase-field model. The continued fracturing that occurs during synkinematic cementation in these veins is simulated using the geometric shift algorithm. The stark resemblance of the numerically sealed vein microstructures with the natural samples in terms of structural characteristics as well as remaining pore space signifies a dominant role of crack opening rates in the resulting morphological patterns. Further, simulation results of slow crack opening rates reveal that non-uniform fibers of variable lengths are formed when initial crack aperture is small, due to suppression of growth competition and vice versa

Effective and Feasible Photocatalytic Degradation of Janus Green B dye in Aqueous Media using PbS/CTAB Nanocomposites

In this Chapter, we demonstrated the synthesis of Lead sulphide by using low-cost chemical displacement method. We used thioacetamide for the source of sulphide ion and for the source metal salt; lead nitrate was used. The structural, morphological, metal percentage and optical properties of as synthesized nanoparticles are investigated by using X-ray diffraction (XRD), Uv-Visible spectra; Field emission gun Scanning electron microscopy (FEG-SEM) with EDS, Fourier transforms infrared spectroscopy (FTIR), High-resolution transmission electron microscopy (HR-TEM) and Photoluminescence spectroscopy (PL).The average particle size of the nanoparticles from the x-ray diffraction is about 20 nm and also field emission gun Scanning electron microscopy shows good morphology and exhibited clearly cubic shape. Further, the photocatalytic degradation of Janus green B dye was measured by visible absorption spectroscopy. To obtain the optimal conditions for the dye degradation, the effect of various experimental parameters, i.e., pH, amount of nanoparticles, concentration of dye and light intensity on the rate of reaction was studied. It was found that the JGB dye degradation gave the best results at a pH of 7.0, dye concentration= 200 ppm and using a 70 mW·cm–2 light intensity with 0.5 g of PbS nanoparticles. At room temperature, the photocatalytic degradation of Janus green B dye was observed about 93.5%